1. Technical Field
The present invention relates to a manufacturing apparatus for an oriented film, a liquid crystal device, and an electronic device.
2. Related Art
A liquid crystal device has been used as a photo-modulation section in a projection display device such as a liquid crystal projector, etc.
Such a liquid crystal device includes a sealant arranged at the periphery between a pair of substrates and a liquid crystal layer sealed at its center.
Electrodes for applying a voltage to the liquid crystal layer are formed on the side of an inner surface of the pair of substrates, and an oriented film for controlling the orientation of liquid crystal molecules when applying a non-selective voltage is formed on the side of the inner surface of the electrodes.
By such a constitution, the liquid crystal device modulates the light of a light source based on the orientation change of the liquid crystal molecules when applying a non-selective voltage or selective voltage to form the light of an image.
An oriented film subjected to a rubbing treatment is generally used as the above-mentioned oriented film on the surface of a polymer film made of polyimides to which a side-chain alkyl group, etc, has been added.
The rubbing treatment section of a polymer is oriented in a pre-determined direction by rubbing the surface of a polymer film in a pre-determined direction with a roller having a soft cloth.
Liquid crystal molecules are arranged along an orienting high polymer due to an intermolecular interaction between the orienting high molecules and the liquid crystal molecules.
Therefore, liquid crystal molecules can be oriented in a pre-determined direction, when a non-selective voltage is applied.
A pre-tilt can be given to a liquid crystal molecule by a side-chain alkyl group.
However, when a liquid crystal device fitted with such an organic oriented film is adopted as the photo-modulation section of a projector, there is concern that the oriented film will gradually degrade due to strong light radiated from a light source or heat.
There is further concern that the orientation control function of liquid crystal molecules is reduced and the display quality of the liquid crystal projector will deteriorate after extended use, e.g., the liquid crystal molecules cannot be arrayed at a desired pre-tilt angle.
Accordingly, the use of an oriented film made of an inorganic material excellent in light resistance and heat resistance has been proposed.
As a manufacturing method for such an inorganic oriented film, for example, a silicon oxide (SiO2) film formed by an oblique evaporation process is known.
When an inorganic oriented film is formed by the oblique evaporation process, it is necessary to control the incidence angle of an oriented film material to form the oriented film in a desired oriented state.
As a technique for controlling the incidence angle of an orientation material, Japanese Unexamined Patent Application, First Publication No. 2002-365639 is known.
According to this technique, a shielding plate having a slit is arranged between an oriented film material and a substrate, through which a desired oriented film is formed by selective evaporation at a pre-determined incidence angle.
However, in the above described technique, the oriented film material is evaporated not only on the substrate but also on the shielding plate, so that a width of the slit of the shielding plate is narrowed after extended evaporating.
By this means, an evaporating condition including the incidence angle regulated by the slit of the shielding plate is changed compared with an initial evaporating condition, irregularities of evaporation or the like occur, and a desired oriented film cannot be obtained.
Furthermore, the oriented film material is adhered in the vicinity of the slit of the shielding plate. If the evaporating is continued in this state, adherent evaporants become floatable particles and adhere to the oriented film. There is concern that the film performance such as the orientation control function is degraded because of this.
To avoid such a disadvantage, it is necessary to frequently perform maintenance on the inside of the apparatus such as changing the shielding plate. However, in this case, there is a new disadvantage such that productivity is lowered.
This is because no matter how the evaporation is performed, while setting the pressure of the inside of the apparatus vacuum, when maintenance for the inside of the apparatus is performed, it is necessary to revert the pressure of the inside apparatus from that of a vacuum to that of the atmosphere.
Therefore, it is necessary to revert the pressure to that of a vacuum by suctioning the air from the inside of the apparatus for performing the evaporation again after maintenance.
However, suctioning the air from the inside of the apparatus takes time. For example, in the case of evaporating a large substrate from which a plurality of substrates is taken, the evaporating apparatus must be large, and there is a substantial need for ten hours to one day to suction the air from the inside of the evaporating apparatus.
Furthermore, in the case of changing the used shielding plate to a new shielding plate, test-evaporation must be performed after changing the shielding plate due to the lowered stability of the initial evaporation. Therefore, there is a problem in that productivity is lost.